Automatic choke



May 12, 1936. G. R. slssoN 2,040,505

AUTOMATIC CHOKE Filed Jan. 20, 1930 Patented May 12, 1936 UNITED ,STATES PATENT OFFICE 18 Claims.

My invention is concerned with the automatic control of the fuel-air ratio in an explosive mixture produced by the carburetor of an internal combustion engine. In my prior Patents No.

i 1,544,350, No. 1,577,765, and No. 1,577,766, I have shown various arrangements by which the mixture proportions may be varied in accordance with the temperature of the engine and the temperature of the atmosphere, and in addition such prior patents disclose means for producing a temporary enrichment of the mixturewhen the engine is being cranked.

Iii a general way, the present invention is concerned with a device similar in purpose to those shown in my prior patents above referred to, and it is the object of the invention of this application to produce a device in the form of an attachment which will be self-contained and which may be brought into association with an ,0 internal combustion engine and its carburetor without the necessity for modification of any of the parts of the engine or carburetor. It is the further object of my invention to produce a device which will overcome certain disadvantages i5 of the devices illustrated in my prior patents.

The accompanying drawing illustrates my invention: Fig. 1 is a fragmental side elevation of an internal combustion engine, such as an automobile engine, showing my device associated with l0 the engine and carburetor; Figs. 2 and 3 are horizontal sections on the lines 2 2 and 3 3 of Fig. 4; Fig. 4 is a vertical section on the line 44 of Fig. 2; Fig. 5 is a diagrammatic view showing electric connections; and Fig. 6 is a fragmental 35 horizontal section on the line 6--8 of Fig. 4.

The engine I0 shown in the drawing has the usual inlet manifold I I and exhaust manifold I2, a carburetor I3 of any desired type being connected to the inlet manifold. v The carburetor has l0 an air inlet conduit I4 and a mixture discharge conduit I5,'flow through the latter being controlled by means of the usual throttle valve I6. A throttle operating rod or wire I1 connected to an arm I8 which is rotatable with the throttle *5 valve I6 serves to maintain the throttle valve in any desired position of adjustment.

If the air inlet conduit I4 of the carbureto is provided with a choke valve, -I contemplate that such valve will either be removed or disconnected from any operating mechanism, as my invention makes manual operation of the choke valve unnecessary.

The device shown in the drawing embodies the invention in my prior Patent No. 1,577,765 in that 5 I r -.ov1de for the carburetor a branched animerpassage, the two branches of which are formed in the body of the attachment, which body iS adapted to be secured as by means of set screws 2l over the air inlet opening of theA conduit I4 of the carburetor. In the body 20, I provide two 5 air passages 22 and 23 which receive air through separate openings but which meet and deliver air jointly to the inlet conduit I4 of the curburetor. p Air flow through the two branch passages 22 and 23 is controlled respectively by valves 24 and 25. l0

.As in my prior Patent No. 1,577,765 one of the valves, here shown as the valve 24, is controlled by temperature-responsive mechanism; and the other valve, here shown as the valve 25, is controlled by means operated jointly with the starter l5 motor associated with the engine I0.

In this application, I contemplate that the position of the valve 24 will be determined in accordance with the temperature of the engine. To this end, the valve 24- is a buttery valve 20 mounted on a vertical shaft 26 which extends upward to a point adjacent the exhaust manifold I2 where it is connected to the inner end of a spirally coiled bi-metallic strip 21, the outer end of which is stationarily, although preferably adjustably, mounted. Desirably, the thermostat 21 is enclosed Within a surrounding casing 28 one side of which is open and in proximity to the exhaust manifold I2. To provide for adjustment of the Vouter end of the thermostat 21, it maybe se- 30 cured as by a bolt 30 to a plate 3| on the outside of the casing 28.- The bolt 30 passes through a slot in the wall of the casing 28 so that the bolt, the plate 3 I and the outer end of the thermostat coil may be moved back and forth and clamped in any desired position of adjustment. The casing 28 which encloses the thermostat 21 may be connected to the body 20 through a tube 26 that encloses the shaft 26.

By reason of the construction just described, 40.

the position of the valve 24 will depend upon the temperature of the engine, since the thermostat 21 is mounted in 4close proximity to the exhaust manifold. When the engine is relatively cold, as it would be after remaining idle for a period of s time, the valve 24 will be closed or nearly closed. When the engine begins to run, the temperature of the exhaust manifold I2 increases, and the thermostat 21 acts to move the valve 24 toward open position. l

' Inorder that the other valve 25 may be controlled jointly with the starter motor associated with the engine I0, I may make it in the form of a butterfly valve mounted on a shaft 35 which also carries an 2armature 36 disposed between the Il illustrated in Fig. 5 may be used. As shownin.

that figure of the drawing, the starter motor 40 is connected in parallel with the electro-magnet 38, and the supply of current from the batteryf4| to the starter 40 and electro-magnet 38 is con'- trolled jointly by the starter switch 42. 'j'.

When the electro-magnet 38 is de-energized, the valve 25 which controls the flow of air through the branch passage 23 desirably occupies a position dependent upon air temperature. To this end, I may associate with the shaft 35 .fa torsion spring 45 which tends to rotate the shaft 35 in a clockwise direction; and I may limit such rotation of the shaft by means of a thermostat 46. 'I'his thermostat is similar to the thermostat 21 in that it is formed of a spirally coiled bi-metallic strip the inner end of which is secured to the shaft 35 and the outer end of which co-operates with an abutment 41 against which it is held bythe action of the torsion spring 45.. The thermostat 46 is arranged in such a manner that as 'the temperature to which it is responsive increases it collapses and permits the spring 45 to move the valve 25 toward open position. y 'I'he armature 36 is so constructed that when the electro-magnet 38 is energized the shaft 35 and the valve 25 will be rotated in a counterclockwise direction against the force exerted by the spring 45 to close the valve 25. When the magnet 38 is de-energized, the spring 45 opens the valve 25, the extent of the opening depending upon the condition of the thermostat 46.

Desirably, the abutment 41 which co-operates with the thermostat 46 to limit opening movement of the valve 25 is not a xed abutment but is adjustable jointly with the throttle valve I6. To this end, the abutment 41 may be in the form of a screw mounted in one arm of a bell crank 50 the other arm of which is connected to the throttle-operating arm I8 through a lost-motion connection 5|. .A torsion spring 52 associated with the bell crank58 tends to rotate such bell crank in a clockwise direction (Fig. 2), or in such a direction as to carry the abutment toward the free end of the thermostat 35. Movement of the bell crank 50 under the influence of the spring 52 is limited, as by arranging it so that it engages the tube 26'. The lost-motion connection 5| is arranged to provide for some opening movement of the throttle without movement of the bell crank 58. When the throttle is opened'beyond a predetermined point, however, the lost-motion provided by the connection 5| is taken up, the bell crank 50 is swung in a counter-clockwise direction, and the resultant movement of the abutment permits the valve 25 to open to agreater exent than it otherwise could. Thus, when the abutment 5| is in engagement with the arm 50 it will cause corresponding movements of the throttle and choke-valve, the choke-valve being moved toward open position as the throttle is moved toward open position, and vice versa.

Desirably, I provide in the circuit of the electromagnet 38 a thermostatic switch 55 which is arranged to open to de-energize the magnet 38 if terial having ai relatively high electrical resistance. ,l f

The strip'56 and/its associated ribbon 51 are conveniently mo'untedyupon a bracket 58 having two ears 59 and 60. The ribbon 51 is insulated from one of these ears, and is connected to one end of the winding ,of the magnet 38. 'I'he other end o f the ribbon s riormally in contact with the ear 60 tol comple ythe connection of the electromagnet tfg resistance ribbon 51, it becomes heated, and the bi-metallicrstrip 56 bends upward to carry the end of ther/ib, 'n 51 out of engagement with the ear 60,"fthusf/ magnet 3,8.. f

In the,Z I, trated'in/th'e positions they occupy when the engine isrelitively cold. The-valve 24 is near its closed position, while the valve 25 is partially open.

If, under such conditions, the starter switch 42 is closed, the starter 40 operates to crank the engine; and simultaneously therewith, the magnet 38 is energized to move the valve 25 toward closed position. This produces a choking eifec't which results in the production of an over-rich mixture in the carburetor, such an over-rich mixture being highly desirable in starting a cold engine. When the engine begins to run on its own power and the starter switch 42 is opened, the electro-magnet 38 is de-energized, and the spring 45 moves the valve 25 toward open .position to (i Iiid. As current flows through the j ning the circuit of the electro- Mving the valves 24 and 25 are illus- I increase the rate of air iiow to the carburetor and to decrease the relative amount of fuel in the mixture which the carburetor delivers to the engine. The extent of this relative decrease in fuel proportion is dependent upon the condition of the thermostat 4E, which in turn is dependent upon air temperature. On a cold day, for example, the opening of the valve 25 which follows the opening of the starter switch 42 will be less than on a hot day. This is desirable, as a relatively rich mixture is demanded when the engine is warming up in cold weather. As the engine continues to -run its temperature increases to cause an increase in the temperature of the exhaust manifold l2. This latter increase in temperature causes the thermostat 21 to open the Valve 24 thus further decreasing the richness of the mixture as the engine warms up.

When the engine reaches its normal operating temperature, the valve 24 will be substantially fully open, so that the supply of air, and therefore the proportions of the mixture produced in the carburetor, will be controlled by the position of the valve 25. In cold weather, this valvewill be more nearly closed than it will in warm weather, thus automatically providing the slightly enriched mixture desirable for the best cold- Weather operation. n

Before the engine is thoroughly warm, the supply` of air to the carburetor I3 is partially choked, and the rate at which the explosive mixture is supplied to the engine is therefore limited by the position of the valves 24 and 25 rather than by the position of the throttle valve. In such circumstances, the position occupied respectively by the valves 24 and 25 limit the maximum speed at which the engine can run. With ein my present invention, however, an extensive opening movement of the throttle valve causes the lost-motion in the connection 5| to be taken up and the abutment 41 to be moved to permit an augmented opening of the valve 25. This increases both the supply of air to the carburetor and the quantity of explosive mixture which the carburetor delivers to the engine and permits the engine to run at the desired high speed.

, Under some circumstances the engine mayfail to start for a reason independent of mixture conditions, and the operator may continue to hold the starter switch 42 closed. 'Ihe continued cracking of the engine with both valves 24 and 25 closed would result in flooding the carburetor. This would produce no benefit and 'might subsequently be the cause .of failure of the engine to start. It is for this reason that the thermostatic switch 55 is provided. As set forth above, this switch opens to de-energize the magnet 3l irrespective ot the condition of the starter switch 42, after the magnet 38 has been energized for a predetermined length of time. I contemplate that this length of time will be insuilicient to accomplish extensive flooding oi' the carburetor.

'A device somewhat similar in purpose to the thermostatic switch 55 is shown in my Patent No. 1,913,131; which issued June 6, 1933. In that patent, however, the temperature responsive detion and for moving said vice is a variable resistance rather than a switch, and eiects gradual control of the choke valve. In addition, the electro-magnet device which moves the choke valve is in circuit with the ignition switch rather than with the starter switch as ln this application. 'I'he claims of my prior patent, however, are not all limited to these features.

I claim as my invention:

1. An attachment for the carburetor of an internal combustion engine, comprising a body adapted to be mounted at the air inlet opening of the carburetor, said body being provided with two air passages both of which communicate with the carburetor air inlet opening when the attachment is in place, a valve in each of said passages, a thermostat supported from said body in position to be responsive to engine temperature when the attachment is in place, said thermostat being operatively connected to one of said valves to control its position in accordance with engine temperature, the other of said valves being biased toward open position, electro-magnetic means for moving said last named valve toward closed position, and a second thermostat for limiting opening movement of said last named valve.

2. In combination with an internal combustion engine carburetor having a throttle valve, a choke valve for varying the quantity of air supplied to said carburetor, said choke valve being biased toward open position, a pair of cooperating abutments for limiting opening movement oisaid choke valve, and temperature responsive means for controlling the position` of one ot said abutments, the other of said abutments being operatively connected to said throttle valve through a lost-motion connection to increase the extent to which the choke valve opens as the throttle valve is opened.

3. In combination with the carburetor oi an internal combustion engine, a rotatably mounted valve biased toward open position for controlling the supply of air to said carburetor, a thermostat rotatable with said valve, an abutment co-operating with said thermostat to .limit opening movement of said valve, and electro-magnetic means for rotating said valve toward closed posisaid abutment. -I

4. 'Ihe invention set forth in claim 3 with the addition that said carburetor is provided with a thermostat away from A throttle'valve, said abutment'being operatively connected to said throttle valve.

5. In combination with an'internal combustion engine carburetor having a throttle valve, a choke valve for varying the quantity of air supplied to said carburetor, said choke valve being biased toward open position, a pair of co-operating abutments for limiting opening movement oi' said choke valve, and temperature responsive means for controlling the position of one of said abutments, the other ot said abutments being operatively connected to said throttle valve.

6. In combination with an internal combustion engine carburetor having a throttle valve, a choke valve for varying the quantity of air supplied to said carburetor, said choke valve being biased toward open position, a pair of co-operating abutments for limiting opening movement o! said choke valve, and temperature responsive means for controlling the position of one of said abutments, the other of said abutments being operatively connected to said throttle valve to increase the extent to which the choke valve lopens as the throttle valve is opened.

'7. In combination with an internal combustion engine carburetor having a. throttle valve and a lchoke-valve, means for controlling the position of said'choke-valve, said means including a device responsive to the temperature of the engine and operative to move said choke-valve toward open position as the temperature of the engine rises, and mechanism operated with said throttle valve when said throttle valve is moving in a range of adjustment near its open position for moving said choke-valve toward open position as the throttle valve approaches open position, said mechanism being inoperative to move said choke valve when said. throttle valve is moving inanother range ci adjustment nearer its closed position.

8. In combination with an internal combustion engine carburetor having a throttle valve, a mixture enrichening device i'or said carburetor, a member, a temperature-responsive element operatively interconnecting said member and said mlxture-enrichening device, a spring acting on said member and biasing said mixture-enrichening device to produce an enriched mixture, and a lost-motion connection between said throttle valve and said member for moving said member and temperature-responsive element to produce a mixture oi' decreased richness when said throttle valve approaches open position.

9. In combination with an internal combustion engine carburetor having a throttle valve, a mixture enrichening device for said carburetor, a member, a temperature-responsive element operatively interconnecting said member and said mixture-enriching device, a spring acting on said member and biasing said mixture-enrichening device to produce an enriched mixture, and a lost-motion connection between said throttle valve and said member for moving said member and temperature-responsive element to produce a mixture of decreased richness when said throttle valve approaches one of its limit positions.

10. In combination with an. internal combustion engine having an electric starter motor, a carburetor i'or supplying explosive mixture to said engine. an electro-magnetic device for varying the proportions of the mixture produced in said carburetor, a switch for jointly controlling the supply of current to said device and said starter motor, and means operated by current supplied to said electro-magnetic device for cutting oir the supply of current thereto at a predetermined time after said switch is closed.

11. In combination with an internal combustion engine having an electric starter motor, a carburetor for supplying explosive mixture to said engine, an electro-magnetic device for varying the proportions of the mixture produced in said carburetor, a time-controlled switch in series with said electro-magnetic device, timingmeans operable at a predetermined time after actuation to open said time-controlled switch, a source of current, and a control switch closable to simultaneously supply current to said starter motor and said electro-magnetic device and to actuate said timing means.

12. In combination with an internal combustion engine having an electricsta'rter motor, a carburetor for supplying explosive mixture to said engine,a device operative to increase the richness of the mixture produced in said carburetor, timing mechanism operative at a predetermined time after actuation to render said device inoperative, and means for simultaneously actuating said timing mechanism and operating said\ device and starter motor.

13. In a control mechanism for a carburetor having a choke-valve biased toward open position, a throttle, a thermostat tensloned to limitI opening movement of said choke-valve and arranged to ease its tension upon an increase in temperature, a spring also tensioned to produce closing movement of said choke valve, and means for relieving the tension of one of said tensioned -elements as the throttle moves into one of its limit positions.

14. In a control mechanism for a carburetor having a choke-valve biased toward open position, a. throttle, la thermostat .tensioned to limit opening movement of said choke-valve and arranged to ease its tension uponv an increase in temperature, a spring also 'tensioned to produce closing movement of said choke valve, and means for relieving the tension of one oi' said tensioned to ease its tension upon an increase in tempera-4 ture, a spring also tensioned to produce closing movement of said choke valve, and vmeans for relieving the tension of said thermostat as the.'

throttle moves into one of its limit positions.

16. In a control mechanism for a carburetor having a choke-valve biased toward open position, a throttle, a thermostat tensioned to limit opening movement of said choke-valve and a1'- ranged to ease its tension upon an increase in temperature, a spring also tensioned to produce closing movement of said choke valve, and means for relieving the tension of said thermostat as the throttle moves into open position. I

17. In combination with an internal combustion engine carburetor having a throttle valve, a choke-valve for said carburetor, a movable member, a temperature-responsive element operatively interconnecting said member and said choke-valve; a spring biasing said member in a direction to close said choke-valve, and means for moving said member Yagainst said spring to produce an opening movement of said chokevalve when said throttle valve approaches one of its limit positions.

18. In combination with an internal combus tionv engine carburetor having a throttle valve, a choke-valve for said carburetor, a movable member, a temperature-responsive element operatively interconnecting said member and said choke-valve, a spring biasing said member in a direction to close said choke-valve, and means for moving said member against said spring to produce an opening movement of said chokevalvewhen said throttle valve approaches open position.

GLEN R. SISSON. 

